The polar night

… is over. At least if you defi­ne the end of the polar night as the day on which ‘civil twi­light’ returns at noon, i.e. the sun is 6 degrees or more below the hori­zon. This was the case yes­ter­day (30 Janu­ary) at just after 12 noon for the first time sin­ce 11 Novem­ber.

Twi­light: civil, nau­ti­cal, astro­no­mic­al

When the sun is lower than -6 degrees around the clock (i.e. 6 degrees below the hori­zon), this is cal­led polar night. Befo­re and after this, the­re are seve­ral weeks when the sun does not rise, but is very low below the hori­zon at mid­day (bet­ween 0 and 6 degrees), so that the­re is a clear twi­light. This is known as ‘civil twi­light’, which peo­p­le expe­ri­ence as dawn. The­re is also nau­ti­cal twi­light (the sun is 6-12 degrees below the hori­zon, which can still be seen by navi­ga­tors at sea) and astro­no­mic­al twi­light (the sun is 12-18 degrees below the hori­zon, which can still be seen by astro­no­mers with a trai­ned eye), and only when the sun is lower than 18 degrees below the hori­zon do we offi­ci­al­ly speak of dark­ness.

In Lon­gye­ar­by­en, it does never hap­pen that the sun is lower than 18 degrees below the hori­zon for 24 hours. Even at the dar­kest time, around 21 Decem­ber, the sun is still bet­ween 11 and 12 degrees below the hori­zon at mid­day, so that when the sky is clear the­re is a hint of twi­light to the south. Strict­ly spea­king, it is never com­ple­te­ly dark for 24 hours in Lon­gye­ar­by­en.

The end of the polar night: view of Hiorth­fjel­let on 30 Janu­ary, spi­ced up with a dose of red light (Ray­leigh-scat­te­ring).

You can read more about this on the cor­re­spon­ding page mid­night sun and polar night.

Pic­tures: the end of the polar night

A few impres­si­ons from yes­ter­day (30 Janu­ary) at noon, alt­hough I had alre­a­dy missed the brigh­test point. The­re was inde­ed a good whiff of that won­derful red light in the air again, alt­hough it wasn’t as inten­se as it was a week ago.

Click on thumb­nail to open an enlar­ged ver­si­on of the spe­ci­fic pho­to.

Red light

I need to come back to the stun­ning phe­no­me­non of the red light again. First­ly, in last week’s post (‘Red sky’) I somehow for­got to men­ti­on the name of the phe­no­me­non that is ulti­m­ate­ly respon­si­ble for this red light. It is cal­led Ray­leigh scat­te­ring. That should be added.

And I also cap­tu­red the red light in a com­ple­te 360 degree pan­ora­ma last week, it just had to be pro­ces­sed first. Here is an exam­p­le from Advent­da­len, at ‘Jern­sen­ga’ (‘the iron bed’, the­re is inde­ed a beds­tead stan­ding in the land­scape. But that is ano­ther sto­ry, for ano­ther day). The­re is ano­ther red light pano on the Inne­rhyt­ta page, taken on a pin­go a litt­le fur­ther into Advent­da­len.

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